The invention relates to a method for manufacturing a photomask, and more particularly to a method for repairing photomask pattern defects.
A photolithography process, which is one process for manufacturing semiconductor devices, uses a photomask having a pattern to be transcribed on a wafer. The photomask has circuit and design patterns of the semiconductor devices The circuit and design patterns of the photomask are transcribed on the wafer by an exposure process. In the exposure process and development process performed to manufacture the photomask, particles may be generated and remain on the surface of a light blocking layer formed on the photomask. The particles remaining on the surface of the light blocking layer may cause defects such as a bridge between patterns of the light blocking layer in the subsequent etching process. Such defects may be transcribed on the wafer in the photolithography process, thereby causing a photomask defect and also forming a defect pattern on a semiconductor substrate.
When the defect pattern is formed in a photomask manufacturing process, a process of repairing the defect pattern is performed. However, as the line width of the semiconductor device becomes smaller, defects occur more easily, and it is difficult to completely eliminate pattern defects. Further, the defect pattern can be repaired into a normal pattern by repeating the steps of repairing the defect pattern, cleaning and inspecting. However, if there is a large defect in the defect pattern, the entire photomask is rejected and a new photomask should be reproduced. Thus, a method of completely eliminating the residue defects caused by the particles in the photomask manufacturing process has been studied.